1. Field of the Invention
This invention relates to a recording method generally called "ink jet recording method", and, more particularly, it is concerned with such recording method which performs recording by discharging and sputtering a recording liquid in the form of fine droplets by the action of heat, and causing the droplets to adhere to the surface of a recording medium.
Recently, a non-impact recording system has drawn attention to all concerned because noises which occur at the time of recording are extremely low to the extent that they are negligible in contrast to an impact recording system such as that represented by typewriters. Of various kinds of such non-impact recording system, an ink jet recording method capable of performing the recording operations at high speed and yet requiring no particular image fixing treatment to plain paper is recognized to be a very promising one. Various systems have so far been proposed for this ink jet recording method, of which various improvements have been made to some of them for commercialization, and efforts are still being made to some others for this practical application.
To make the matter short, the ink jet recording method is to perform the recording by ejecting and sputtering droplets of a recording liquid called "ink" through a fine orifice (or orifices), and causing it to adhere onto the surface of the recording member. This ink jet recording method is classified into several types depending on its method of generating droplets of the recording liquid, its method of controlling the sputtering direction of the droplets thus produced, and others.
2. Description of the Prior Art
Heretofore, the so-called "heat sensitive recording system" which utilizes heat generation from a thermal head has been widely adopted in various printers, facsimiles, and so on.
This recording system is such that the thermal head is contacted to a recording paper prepared by forming a layer of heat sensitive recording material on an arbitrary substrate such as paper, etc., and a thermal information input is introduced through this thermal head to obtain a color formed image on the recording paper. In more detail, a signal generated in a power source is first transmitted to the thermal head through an electrical circuit. In this case, a resistor in the thermal head produces heat, and an image in conformity to the signal is obtained in the recording layer.
The advantages in the above-mentioned heat-sensitive recording system are as follows: (1) a primary color forming recording material is used; (2) the device is of maintenance-free type; (3) the recording material is cheap in price, and its handling is also easy; (4) the device can be reduced in size; (5) noiseless recording operation can be carried out in view of its being of a non-impact type; (6) the recording system including the device per se can be obtained at a low cost. On the other hand, however, this heat sensitive recording system has the following disadvantages.
The total disadvantage which has so far been known with respect to the heat sensitive recording is that, among other things, its printing speed is very slow in comparison with other recording methods. For example, the heat pulse which is practically used is of an order of 10 m sec to 20 m sec. Even for particularly high printing speed, it is of an order of 5 m sec to 6 m sec at best. In addition, the result of printing by this heat sensitive recording method, i.e., quality of the resulted image, cannot be said to be satisfactory. In particular, this heat sensitive recording system is almost incapable of performing image recording with a high image resolution. Thus, with the conventional heat sensitive recording system, it has not yet been made possible to perform the image recording with high image quality and at a high recording speed, in the true sense of the words.